The present invention relates in general to an image display device, and, more particularly, the present invention relates to an image display device provided with a support body which is inserted between substrates and surrounds a sealed space forming a display region.
As an image display device which exhibits high brightness and high definition, a color cathode ray tube has been popularly used conventionally for many years.
However, along with recent improvements in the high quality of information processing equipment and television broadcasting, there has been a demand for a flat-panel-like display device (panel display) which possesses excellent properties, such as high brightness and high definition, and which is light-weight and requires a small space for installation.
As a typical example of such a flat-panel-like display device, a panel display device such as a liquid crystal display device, a plasma display device or the like, has been put into practical use.
Among these types of panel display devices, various types of devices have been proposed, including a field (electron) emission type display device, which is particularly capable of exhibiting high brightness, an organic EL display device, which is characterized by low power consumption, and the like.
Among such panel-type display devices, in display device in which a sealed space is defined between two substrates consisting of a face substrate and a back substrate, and in which an inner pressure of the sealed space is set to be lower than the ambient atmospheric pressure or in which a vacuum is created in the sealed space, there is provided a support body which maintains a gap between the two substrates at a given value and, at the same time, maintains the hermetic property by surrounding the sealed space.
FIG. 18 is a cross-sectional view showing one example of a known field-emission-type image display device. In FIG. 18, the field-emission-type image display device is configured such that a frame-like support body 3, which is formed as an integral body, is inserted between inner peripheral portions of a back substrate 1 and a face substrate 2, which faces the back substrate 1 in an opposed manner; the support body 3 is sealed to the back substrate 1 and the face substrate 2 using a sealing material 4; and the inner space, which is surrounded by the support body 3 and defines a display region, is held at a pressure lower than the ambient atmospheric pressure or in a vacuum state.
The image display device includes field-emission-type electron sources 5, control electrodes and the like formed on an inner surface of the back substrate 1, and, at the same time, anodes and phosphor layers 6 are formed on an inner surface of the face substrate 2. Further, numeral 7 indicates spacers which serve to maintain a predetermined distance between both substrates within the display region.
The back substrate 1 is preferably made of a material such as glass, ceramics or the like, while the face substrate 2 is preferably made of a material having optical transmissivity, such as glass or the like. Further, the support body 3 is preferably made of a material such as glass, ceramics or the like and is fixed to the inner peripheries of the back substrate 1 and the face substrate 2 using a sealing material 4 made of frit glass or the like. The inner space defined by the back substrate 1, the face substrate 2 and the support body 3 is evacuated to a degree of vacuum of, for example, 10−5 to 10−7 Torr. Further, the above-mentioned electron sources 5 are formed of, for example, carbon nanotubes (CNT), diamond-like carbons (DLC) or other field-emission-type cathode materials.
In such a panel display device, with respect to the support body which surrounds the display region and which reserves to maintain a predetermined distance between both substrates, the above-mentioned integral-body-type support body and a support body which is constituted by joining a plurality of wall members, as shown, for example, in FIG. 19, have been employed.
FIG. 19 is a diagram showing a display device which is disclosed in Japanese Patent Laid-open 2002-298761 (patent literature 1) and is a developed perspective view showing an example of the back substrate 1, the face substrate 2 and the support body 3.
In the display device shown in FIG. 19, the back substrate 1 and the face substrate 2 are each formed of a glass plate, while the support body 3 is formed of a glass material. Here, various structural elements which are formed on the respective inner surfaces of the back substrate 1 and the face substrate 2 are omitted from the drawing.
In FIG. 19, the support body 3, having a given thickness, is inserted between the peripheries of the back substrate 1 and the face substrate 2, and the support body 3 is sealed to the back substrate 1 and the face substrate 2 using a sealing material so that a fixed gap is provided between the back substrate 1 and the face substrate 2, thus forming a sealed space in the inside thereof. The support body 3 is divided into a plurality of wall members 3X1, 3X2, 3Y1, 3Y2, 3C1 to 3C4.
On portions where the respective wall members 3X1, 3X2, 3Y1, 3Y2, 3C1 to 3C4 are arranged close to each other and are engaged with each other, inclined surfaces 3P are formed. Further, an intersecting angle, which is established between a normal line which is erected from the inclined surface 3P and a normal line which is erected from the back substrate 1 or the face substrate 2, is set to an acute angle.
FIG. 20A, FIG. 20B and FIG. 20C are three views showing the support body shown in FIG. 19, wherein FIG. 20A is a plan view, FIG. 20B is a short-side side view and FIG. 20C is a long-side side view. Symbols used in these drawings correspond to the symbols used in FIG. 19.
As shown in FIG. 20A, FIG. 20B and FIG. 20C, the support body 3 of this example is divided into two long-side wall members 3X1, 3X2, two short-side wall members 3Y1, 3Y2, and four corner wall members 3C1, 3C2, 3C3, 3C4. The support body 3 is constituted by securing these members to each other at the respective inclined surfaces 3P using an adhesive, for example.
Further, Japanese Patent Laid-open 2000-311630 (patent literature 2) discloses a technique in which a display device includes a first frame member which embraces electron emission elements and a second frame member which embraces the first frame member. These first and second frame members are positioned and fixed by arranging a plurality of plate-like members in a rectangular shape, and respective contact portions are melted using a burner, thus forming a support body by welding.
Further, Japanese Patent Laid-open 2000-184329 (patent literature 3) discloses a technique in which a side wall is provided between a face substrate and a back substrate; a background layer and an indium layer made of a metal sealing material are stacked and arranged on a sealing surface between the side wall and the face substrate; and at least one of the background layer and the indium layer includes a projecting portion which projects from the sealing surface. When an extra metal sealing material is generated at the time of sealing both substrates by heating and melting indium in a vacuum atmosphere, the extra metal sealing material is extended to the projecting portion, thus preventing the extra metal sealing material from flowing out to the electron sources and lines.